This application is based on and claims priority under 35 U.S.C. xc2xa7 119 with respect to Japanese Patent Application No. 10(1998)-355198 filed on Dec. 14, 1998, the entire content of which is incorporated herein by reference.
The present invention generally relates to a vehicle slide door. More particularly, the present invention pertains to a drive device for vehicle slide doors.
Japanese Patent Laid-open Print No. Hei. 10-266697 discloses a drive device for a vehicle slide door that includes a shaft which is coupled to a slide door by way of a clutch mechanism. When an electric motor is turned on in one direction, the resulting rotation of the motor output shaft is transmitted to the slide door via the shaft for opening the slide door. When the electric motor is turned on in the opposite direction, the resulting rotation of the motor output shaft is transmitted to the slide door via the shaft for closing the slide door. To determine the displacement or degree of movement of the slide door, the amount of rotation of another shaft which is coupled with the shaft by way of a belt is checked.
However, the belt is formed from rubber and thus tends become loose or shrinks to some extent depending on surrounding temperature and changes in the surrounding temperature. This means that the rotation of the shaft cannot be transmitted to the other shaft with perfect precision. As a result, it may not be possible with this known drive device to correctly determine the displacement or degree of movement of the slide door.
Accordingly, a need exists for a drive device for vehicle slide doors in which the rotation of the shaft can be determined with a relatively great degree of accuracy and precision so that the position of the slide door can be accurately ascertained.
In light of the foregoing, a drive device for a vehicle slide door according to the present invention includes a shaft that is journalled in a casing, coupled to an electric driving source by way of a clutch mechanism for receiving a force, and moves the slide door by using the force, an output gear mounted on the shaft to rotate together with the shaft, a rotor accommodated in the casing and rotated together with the shaft, and a movable plate that is accommodated in the casing for rotation relative to the shaft and that is adapted to be coupled to the rotor in a detachable manner. An armature is secured to the movable plate, and an electric coil winding device is secured to the casing in opposition to the armature via the rotor. The electric coil winding device cooperates with the armature and the rotor to constitute a magnetic closed loop which attracts the armature toward the rotor to thereby couple the movable plate and the rotor. A magnetic member is secured to the rotor to be located outside the magnetic closed loop, and a sensor is secured to the casing and has a Hall element for detecting the rotation of the rotor.
The magnetic member is preferably in the form of a ring-shaped magnet whose periphery is provided with alternatively arranged N-poles and S-poles.
According to another aspect of the invention, a drive device for a vehicle slide door includes a rotatable shaft journalled in a casing and coupled to an electric driving source by way of a clutch mechanism for receiving a rotational force, an output gear mounted on the shaft for rotation together with the shaft, a cable connectable to the slide door and engaged by the output gear, a magnetic member operatively associated with the shaft so that rotation of the shaft causes rotation of the magnetic member, and a Hall element mounted in opposing relation to the magnetic member to sense rotation of the shaft.
In accordance with another aspect of the invention, a vehicle slide door apparatus includes a slide door mounted on a lateral side of a vehicle body for movement in a lengthwise direction of the vehicle body between an open position and a closed position, a connecting cable connected to the slide door to move with the slide door, and a rotatable shaft journalled in a casing, an output gear mounted on the shaft for rotation together with the shaft. The connecting cable engaged by the output gear so that the output gear and the connecting cable move together. A magnetic member is operatively associated with the shaft so that rotation of the shaft causes rotation of the magnetic member, and a sensor is mounted in opposing relation to the magnetic member to sense rotation of the shaft based on rotating movement of the magnetic member.